There Are Limits to How High You Can Set Your Dryer
Be warned that there is a temperature limit that you can set your dryer to for handling wetter-than-usual high-moisture corn.
“Be aware that higher drying temperatures may result in a lower final test weight and increased breakage susceptibility,” cautions Ken Hellevang of North Dakota State University. “In addition, as the drying time increases with high-moisture corn, the corn becomes more susceptible to browning.”
Maximum recommend drying temperatures depend on the drying system you are using.
- For continuous flow and recirculating batch dryers, that temperature (for corn) would 200°F. to 210°F.
- For column batch dryers, the maximum temperature is 180°F. (for corn).
- For bin batch dryers, the maximum temperature (for corn) is 120°F.
You can crank up your dryer to run at higher temperatures to get higher-than-usual moisture corn down to storage levels. But that higher temperature can come at a loss of potential kernel damage.
An alterative to increasing drying capacity is to cool grain in storage. The huge advantage of in-bin cooling is that dryer capacity is increased 20% to 40%, and about 1% of moisture is removed during corn cooling.
In-storage cooling requires a positive-pressure airflow rate of about 0.20 cubic feet per minute per bushel (cfm/bu) or 12 cfm/bu per hour of fill rate. Cooling should be started immediately after corn is placed in the bin from the dryer.
Any dryer using an open flame does pose a constant fire hazard, Hellevang warns. To minimize fire potential you need to clean the dryer, air ducts, and area around the dryer at least daily.
Another warning is that most moisture meters have accuracies of plus or minus .5% under normal operating conditions. But high grain drying temperatures affect the accuracy of moisture meter readings. The grain closest to the meter’s calibration temperature, often about 75°F., gives more accurate readings than grain at higher or lower temperatures.
Points to remember when using moisture testers:
- When testing during or immediately after drying, the reading is probably in error.
- Find the moisture content of several samples for the lot of grain being checked.
- Do not handle the sample with your hands (this adds moisture) or expose it to air in an open container (this causes some drying or wetting to occur).
- Weigh or measure the sample accurately if required.
- Use proper procedure for temperature correction if necessary.
North Dakota State University offers a comprehensive grain drying guide at https://www.ag.ndsu.edu/publications/crops/grain-drying#section-6.